In recent years, disturbance of maritime traffic has been found in coastal areas where various structures such as bridges and reclaimed airports are planned and being constructed. In this study, we have proposed a new concept of a maritime traffic survey system using a device and information processor which can operate a radar to arbitrarily record and reproduce the images. This system's reproduction ability that enabled the analysis of images by reproduction method, particularly in the laboratory, was confirmed and proved effective. In addition to the traffic analysis method that already reported, we have developed an interface connecting the radar and computer, and a processing program for the purpose of using computer to process the observation result. This development enabled the computer processing of a target on a radar PPI in the laboratory, which was difficult in the past. As a practical case, we worked on the construction of a bridge at the AKASHI Channel and studied the image processing to analyze the type of vessels from the radar image information.As a result, we succeeded in presuming the size of vessels using the formula of a linear multiple regression model. Aready, the maritime traffic analysis using this system has been applied to the aforementioned bridge to analyze the construction influence and provide the data base. It can be said that this study developed a new phase for the use of the computer analysis. The second subject of this study is the disturbance and problems of the propagation anaomalies of Decca and Loran-C navigation system, as new problem are to such electronic navigation system by maritime structures including huge bridges.